Gum base

ABSTRACT

The invention relates to chewable gum base compositions, to chewing gums containing them, and to processes for preparing them. The gum base compositions comprise (a) a polyvinyl acetate matrix, in which the polyvinyl acetate is in the form of a continuous phase, and (b) casein, a modified casein, or both casein and a modified casein, wherein particles of casein and/or modified casein are dispersed throughout the polyvinyl acetate matrix. 
     In preferred embodiments the gum base compositions also contain polyglycerol polyricinoleate, mono- and di-glycerides esterified with mono-acetyl and di-acetyl tartaric acid, acetylated monoglycerides, lecithin and sodium or calcium stearoyl-2-lactylate. Chewing gums of the present invention contain a chewable gum base as described above, in combination with one or more sweeteners and/or flavouring agents, and preferably also glycerol triacetate and stearic acid.

FIELD OF THE INVENTION

This invention relates to new chewable gum base compositions, toproducts made from such compositions, in particular to chewing gums, andto processes for preparing same.

BACKGROUND OF THE INVENTION

Chewing gum is a popular consumer product, because of its taste and thechewing sensation that it provides. However, conventional chewing gums,when spent, have a strong tendency to stick to surfaces such as carpetsand sidewalks, and retain their stickiness for a considerable period oftime. They are also non-biodegradable. Accordingly, conventional chewinggums, if disposed of improperly, can cause an unsightly litter problemthat is difficult to remove. This has led to restrictions on the sale ofconventional chewing gums in some countries.

It would therefore be desirable to provide a chewing gum which goes someway towards overcoming these problems, while at the same timemaintaining good chewing properties and therefore acceptability toconsumers.

WO 98/15189 of Warner Lambert Company discloses a process in which ablend of a protein component and a plasticizer component is heated undercontrolled shear conditions to form a plasticized proteinaceousmaterial, which may be used for producing gums and confectionerycompositions.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a gum basecomposition which goes some way towards meeting the above desiderata, orat least to provide the public with a useful choice.

Accordingly, in one aspect, the present invention provides a chewablegum base composition comprising (a) a polyvinyl acetate matrix, whereinthe polyvinyl acetate is in the form of a continuous phase, and (b)casein, modified casein, or both casein and a modified casein, whereinparticles of casein and/or modified casein are dispersed throughout thepolyvinyl acetate matrix.

In a preferred embodiment, the gum base composition contains acidcasein. In a particularly preferred embodiment, the gum base containsboth acid casein and fine ground acid casein.

In another preferred embodiment, the gum base contains both acid caseinand acid casein which has been polymerised using transglutaminase, orhydrolysed acid casein which has been polymerised usingtransglutaminase.

It is particularly preferred that the polyvinyl acetate comprises ablend of polyvinyl acetates having differing molecular weights.

In addition, the gum base composition preferably includes one or morenon-toxic plasticizers and/or emulsifiers. Preferably, the gum baseincludes mono- and di-glycerides esterified with mono-acetyl anddi-acetyl tartaric acid (Datem), acetylated mono- and/or di-glyceridesand polyglycerol polyricinoleate.

In a particularly preferred embodiment, the gum base composition furtherincludes the additional emulsifiers lecithin and sodiumstearoyl-2-lactylate or calcium stearoyl-2-lactylate.

It is also preferred that the gum base composition includes atexturiser, conveniently calcium chloride, which is convenientlycombined with the casein or modified casein prior to formulation of thegum base.

The gum base composition preferably also includes a filler such as talc.

In another aspect, the invention provides a confectionery productcontaining a chewable gum base composition as defined above.

In a further aspect, the present invention provides a chewing gumcontaining a chewable gum base composition as defined above.

In a preferred embodiment, the chewing gum further comprises glyceroltriacetate and stearic acid, in combination with one or more sweetenersand/or flavouring agents.

In a further aspect the present invention provides a process forpreparing a chewable gum base composition comprising particles of caseinand/or modified casein dispersed throughout a polyvinyl acetate matrix,the process comprising the steps of heating polyvinyl acetate, togetherwith one or more plasticizers and/or emulsifiers that are suitable toplasticize the polyvinyl acetate, to a temperature sufficient to meltthe polyvinyl acetate, and mixing casein, a modified casein, or bothcasein and a modified casein with the molten polyvinyl acetatecomposition, to form a homogenous composition.

Preferably, the polyvinyl acetate is initially heated to a temperatureof between about 55° C. and about 110° C. with the one or moreplasticizers and/or emulsifiers.

Preferably the casein and/or modified casein are added after thepolyvinyl acetate is molten, and the casein and/or modified casein aremixed in to the composition while the composition is at a temperature offrom about 40° C. to about 90° C.

Preferably, the process includes the additional step of adding one ormore further emulsifiers to the composition, preferably after the caseinhas been mixed into the composition.

Preferably, the process further includes the additional step of adding afiller such as talc to the composition, preferably after mixing of thecasein into the composition.

Preferably, the casein and/or modified casein is mixed with atexturising agent, preferably calcium chloride, before combining it withthe polyvinyl acetate composition.

In further aspects, the present invention provides a chewable gum baseobtainable by a method as defined above, and a chewing gum includingsuch a gum base.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is broadly as defined above, it will be appreciatedby those persons skilled in the art that it is not limited thereto butthat it also includes embodiments of which the following descriptionprovides examples.

This invention relates to a non-toxic, chewable gum base composition andto products containing the gum bases, and in particular to chewing gums.The chewable gum bases of the present invention contain casein, or amodified casein, or both, and the gum base is in the form of particlesof casein or modified casein dispersed throughout a polyvinyl acetatematrix.

The applicants have surprisingly found that a non-toxic, chewable gumbase, having very good cohesion and chewing properties, can beformulated by providing a composition in which particles ofcasein/modified casein are dispersed substantially uniformly throughouta polyvinyl acetate matrix. In the compositions of the presentinvention, the polyvinyl acetate is present, together with one or moreplasticizers and/or emulsifiers, as the continuous (plasticized) phaseof the gum base, and particles of casein/modified casein, generally inthe form of aggregates of casein/modified casein molecules, aredispersed throughout this continuous phase. The casein/modified caseinitself is not substantially plasticized or in the form of a continuousphase.

It is believed that the casein or modified casein particles contributeto the texture and chewing properties of the gum base composition byimparting a degree of “rubberiness”, and also bulkiness, to thecomposition.

Chewing gums made from such gum base compositions also have theadvantage that they are sufficiently non stick that they can be easilyremoved from most surfaces including carpet, clothing and hair.

The gum base compositions of the invention have also been found to bedisintegratable and are made of substantially biodegradable components.

The chewable gum base compositions of the present invention will now bedescribed in more detail.

As defined above, the chewable gum base formulations of the inventioncontain casein or a modified casein, or both. In a preferred embodimentof the invention, the casein is simply acid casein. For example, 80 meshcasein (100% with a particle size of less than 250 microns, and 85% witha particle size less than 180 microns) may be used. In a particularlypreferred embodiment, the gum base comprises both acid casein and fineground acid casein (for example, having a particle size less than about10 microns).

The addition of some fine ground acid casein in addition to acid caseinhas been found to increase the smoothness of the resulting gum base,although it is desirable to have some casein in the gum of a largerparticle size such as 80 mesh, to retain good chewing properties.Without wishing to be bound by any theory, it is believed that largerparticles of casein may enable a more constant level of rubberiness inthe gum base by absorbing moisture more slowly than smaller particles onchewing.

In alternative embodiments the casein can be modified, for example byenzymatic or chemical cross-linking, to control the degree of swellingof the casein. This in turn may enhance the “rubberiness” of the gumbase, while at the same time allowing a smaller particle size of caseinto be used and thereby resulting in a smoother gum.

In alternative preferred embodiments, the gum base includes both acidcasein and a modified casein. In these embodiments, the modified caseinis preferably acid casein which has either been polymerised using theenzyme transglutaminase, or acid casein which has first been hydrolysedusing a suitable enzyme, preferably trypsin, and then polymerised usingtransglutaminase.

In this specification, the term “modified casein” includes a caseinwhich has been treated with one or more enzymes and/or chemicals (suchas hexanal or acetic anhydride) to alter its structure, for example topolymerise it and thereby produce a casein with a higher molecularweight. Specific examples of modified caseins suitable for use in thegum base compositions of the present invention include (but are notlimited to), polymerised hydrolysed casein, polymerised casein,thiolated casein, hexanal-modified casein and palmitoyl-modified casein.The term “modified casein”, as used herein, also includes caseinatessuch as sodium caseinate and calcium caseinate.

For the avoidance of doubt, the term “casein”, as used herein, includesboth acid casein and rennet casein.

In alternative embodiments, the gum base may include another protein orproteins, in addition to the casein/modified casein. Other proteinswhich can optionally be included with the casein/modified casein in thegum base formulation are protein-containing whey derivatives (such aswhey protein isolates and whey protein concentrates), wheat gluten andwheat protein isolates.

It is generally preferred that the casein or modified casein, orcombination of casein and modified casein, is present in the gum base ina total amount in the range of from about 5% to about 30%, morepreferably, about 12–16.5%, by weight of the total ingredients includedin the gum base formulation.

If an additional protein such as wheat gluten is included, this ispreferably present in an amount of from about 4% to about 13% by weightof the formulation.

It is also generally preferred that a texturising agent which interactswith the casein/modified casein is included. Conveniently, thetexturising agent is calcium chloride. It is preferred that the calciumchloride is present in an amount of up to about 1.5% by weight of thetotal ingredients in the gum base formulation, more preferably about0.4%–0.6% by weight. Other suitable calcium salts and divalent cationswill be apparent to those skilled in the art.

The gum bases of the present invention also contain polyvinyl acetate,which provides both substance and extensibility to the gum base.Preferably, the polyvinyl acetate has a molecular weight ranging fromapproximately 12,000 to approximately 40,000. It is generally preferredthat the polyvinyl acetate is present in an amount from about 20% to65%, more preferably about 35% to about 56%, by weight of the totalingredients included in the formulation. It is also preferred that acombination of polyvinyl acetates having different molecular weights isused. In one particularly preferred embodiment, a combination of fourpolyvinyl acetates having molecular weights of approximately (1) 12,900,(2) 14,000, (3) 25,000 and (4) 40,000 respectively is used in the gumbase. These four polyvinyl acetates are preferably present in the gumbase composition in proportions in the ranges of: (1) up to about 25% byweight; (2) up to about 25% by weight; (3) about 12%–25% by weight; and(4) about 5% to about 18% by weight, respectively.

The gum base formulation of the present invention also includes one ormore emulsifiers and/or plasticizers.

Suitable plasticizers and emulsifiers include mono- and di-glyceridesesterified with mono-acetyl and di-acetyl tartaric acid (Datem),polyglycerol polyricinoleate, acetylated mono-and/or di-glycerides,sodium and calcium stearoyl-2-lactylate, lecithin, liquid acetylatedmonoglycerides, polysorbate 60, mono- and di-glycerides esterified withcitric acid and mono- and di-glycerides esterified with lactic acid andsodium deoxycholic acid. It will be appreciated that these compounds mayfunction as both emulsifiers and plasticizers for polyvinyl acetate.

It is preferred that the gum base of the present invention contains bothpolyglycerol polyricinoleate and Datem. It is more particularlypreferred that the gum base contains the following combination ofemulsifiers and plasticizers: (1) Datem, (2) acetylated mono and/ordi-glycerides, and (3) polyglycerol polyricinoleate, present in amountsof (1) from about 1 to about 24% by weight, more preferably from about1-about 15% by weight, (2) up to about 24% by weight, more preferablyabout 1- about 10% by weight, and (3) from about 4.4 to about 20% byweight, more preferably about 6–11% by weight, respectively, of thetotal ingredients in the gum base formulation.

A preferred acetylated monoglyceride is that known as MYVACET 7-07™,which is produced from hydrogenated vegetable oil, has a melting pointbetween 37° C. and 40° C. with a percent acetylation of between 66.5 and69.5.

It is also particularly preferred that, in addition, the gum baseformulation of the present invention includes both lecithin (preferablya lecithin with a relatively high solubility in acetone, such as thatknown as Emulpure N or Emulgum™, which are deoiled soybean lecithinshaving a minimum phospholipid content of 95% and an acetone insolublecontent of 95% minimum), present in amounts of up to about 6% by weight(more preferably about 2 to about 4% by weight), and sodiumstearoyl-2-lactylate or calcium stearoyl-2-lactylate, present in amountsof up to about 5% by weight (more preferably about 0.5 to about 3% byweight) of the total ingredients in the formulation.

The above combination of surfactants and plasticizers has been found tobe particularly effective in plasticizing the polyvinyl acetate andmaintaining an emulsion.

It is also preferred that the gum base of the invention includes afiller. Examples of suitable fillers include talc, calcium carbonate,magnesium carbonate, alumina, tricalcium phosphate and synthetic ornatural clay, and mixtures thereof. A preferred filler is talc. Theamount of talc present should be effective to provide a cohesive gumbase with good chewing properties. It is generally preferred that thetalc is present in an amount of up to about 25% by weight, morepreferably about 7–13% by weight, of the total ingredients in theformulation.

Other components can also optionally be included in the gum baseformulation if desired. Other optional components which can be includedin the gum base are:

-   paraffin and micro-crystalline waxes at levels up to 5.0% by weight;-   hardened fats at levels up to 2% by weight;-   polycaprolactone (biodegradable polymer) at levels up to 2.0% by    weight;-   guar gum, at levels up to 0.5% by weight; and-   locust bean gum at levels up to 0.5% by weight.-   terpene resin at levels up to 2% by weight-   carrageenan at levels up to 2% by weight.-   Polyisobutylene (having a relative molar mass of 40,000) at levels    up to 1% by weight.-   Lanolin, at levels up to 3% by weight.    Preparation of Chewable Gum Base Composition

As described above, the chewable gum base compositions of the inventioncontain casein and/or modified casein particles dispersed throughout apolyvinyl acetate matrix. The polyvinyl acetate matrix is present in thegum base as a continuous phase.

The gum base compositions of the present invention may be prepared bycombining polyvinyl acetate with one or more plasticizers and/oremulsifiers suitable to plasticize the polyvinyl acetate, at atemperature sufficient to melt the polyvinyl acetate. It is generallypreferred that the polyvinyl acetate be heated to a temperature of fromabout 55° C.–140° C., more preferably about 70° C.–110° C. Theplasticizers/emulsifiers and polyvinyl acetate are preferably mixeduntil the polyvinyl acetate is molten and a homogeneous mixture isobtained.

Casein and/or a modified casein is also added to the composition, whichis then mixed until visually homogeneous. It is preferred that thecasein/modified casein is added after the polyvinyl acetate is molten.The casein/modified casein is preferably added in a dry form, andpreferably, before adding it to the composition, the casein is firstmixed with a texturising agent such as calcium chloride.

It is generally preferred that, after the casein modified/casein isadded, the mixing is carried out with the composition at a lowertemperature, preferably between 40–90° C. (to minimise heat damage tothe casein particles and consequent possible production of offflavours). Once a homogeneous, cohesive mixture has been obtained, theresulting mass is preferably removed from the heat, and additionalemulsifiers may be added, with slow mixing, preferably when thetemperature of the mass reaches about 55° C. A filler may then be addedslowly, preferably when the temperature of the base reaches between 40°C.–80° C., and the mass mixed until it is homogeneous.

The shear levels that can be used to mix the gum base are similar tothose used to mix conventional gum bases known in the art. However, asthe lower temperatures preferably used when mixing the casein into thecomposition will result in the composition becoming more viscous, highershear levels may then be required to achieve adequate mixing.

In one preferred embodiment, a method of preparing a chewable gum baseformulation of the present invention is as follows: A BrabenderPlasticorder (W 50 mixer, cam blades) is used with an initialtemperature of approximately 100° C., and an initial speed ofapproximately 60 RPM. The acetylated monoglycerides, sodium or calciumstearoyl-2-lactylate, Datem and paraffin (if used) are added first,followed immediately by the polyvinyl acetates, and the temperature isthen reset to approximately 60° C. The casein and calcium chloride areadded at approximately 3 minutes. The speed is decreased toapproximately 40 RPM just before adding the polyglycerol polyricinoleateand lecithin at approximately 8 minutes. Lastly the filler (eg talc) isadded at approximately 9 minutes, and mixing is stopped at approximately10 minutes.

In another preferred embodiment, a method of preparing a chewable gumbase formulation of the present invention is as follows: A BrabenderPlasticorder (W 50 mixer, cam blades) is used with an initialtemperature of approximately 100° C., and an initial speed ofapproximately 60 RPM. The acetylated monoglycerides, sodium or calciumstearoyl-2-lactylate, Datem and paraffin (if used) are added first,followed immediately by the polyvinyl acetates, and the temperature isthen reset to approximately 40° C. The speed is decreased to 40 RPM at 4minutes. The polyglycerol polyricinoleate and lecithin are added atapproximately 7 minutes and the filler (eg talc) is added at 8 minutes.The casein and calcium chloride are added at approximately 9 minutes andmixing stopped at 11 minutes. The gum base temperature is approximately70° C. when the casein and calcium chloride are added and approximately72° C. when the mixer is stopped.

If desired, prior to preparation of the gum base, the casein/modifiedcasein to be used may be treated to remove low molecular weightmaterial, for example by resuspending the casein in water followed bydiafiltration. The pre-treatment may result in the gum base having acleaner flavour. A suitable method for pretreatment of the casein is asfollows: Dried casein or de-watered casein curd is suspended in water(to give about 5–10% total solids) and the pH adjusted to between 7.0and 7.5 and heated to 50° C. until dissolved. The solution is cooled toapproximately 5° C. and diafiltered (approximately 6 theoretical volumechanges). The pH is adjusted to 4.6 with hydrochloric acid, heated to50° C. and filtered. The recovered curd is dried (eg freeze dried) andground to the desired particle size.

In the resulting gum base, the polyvinyl acetate forms the continuous,plasticized phase, throughout which individual particles of thecasein/modified casein are dispersed.

Preparation of Ch Wing Gum

Chewing gums according to the invention can be prepared from thechewable gum bases described herein using conventional processes knownin the art. These generally involve adding one or more sweeteners and/orflavouring agents to the gum base. The chewable gum base formulations ofthe present invention are suitable for making into either sugarlesschewing gums or sugar-containing chewing gums.

The chewing gums of the invention preferably contain the gum base in anamount from about 15% to about 90% by weight, more preferably about 20%to about 50% by weight and still more preferably about 24% to 35% byweight of the chewing gum.

In one embodiment, a chewing gum of the invention is prepared by meltingthe gum base with a liquid sweetener, conveniently glucose syrup, at atemperature of from about 45° C. to 65° C., accompanied by mixing. Thisis followed by the incremental addition of small amounts of a furthersweetener in solid form, conveniently glucose powder or powderedsucrose, and flavouring agents. If desired, maltodextrin (having adextrose equivalent of between 20 and 25) may be substituted for glucosesyrup at a rate of from about 9% to 18%. The reduced moisture contenthas been found to reduce stickiness and improve the chewing propertiesof the resulting gum.

Alternatively, the chewing gum of the invention may be prepared byincorporating the sweeteners and flavourings in the gum base using asuitable mixer. For example, a Brabender Plasticorder, fitted with a W50 mixer (cam blades) and operated at a temperature of about 45° C. anda speed of 50 RPM can be used to produce a chewing gum according to thefollowing steps:

-   1. The gum base and glucose syrup are mixed for 2 minutes;-   2. 33% of the powdered sucrose is added, and mixed for 2 minutes;-   3. 33% of the powdered sucrose is added with 50% of the flavours,    and mixed for 3 minutes;-   4. 33% of the powdered sucrose is added with 50% of the flavours,    and mixed for 2 minutes; and-   5. The gum mass is removed from the mixer and rolled to a thickness    of 2–3 mm.

In a particularly preferred embodiment, the additional componentsglycerol triacetate (preferably in an amount of from about 0.5 to 4%,more preferably about 0.75% to 2.5% by weight of the final chewing gum)and stearic acid (preferably in an amount of from 0.5% to 1.5% by weightof the chewing gum) are also included into the chewing gum. Thecombination of glycerol triacetate and stearic acid has been found toimprove the cohesion properties of the resulting chewing gum. Whereglycerol triacetate and/or stearic acid are included, these arepreferably added in step 1 of the above method.

The invention will now be further described with reference to thefollowing non-limiting examples.

EXAMPLES Example 1

Ingredient % (weight/weight) Polyvinyl acetate (MW ~25,000) 35.5 Datem*13.8 Acid casein 13.8 Wheat gluten 12.0 Polyglycerol polyricinoleate 8.9Acetylated monoglycerides (Myvacet 7-07) 9.2 Lecithin (Emulgum) 3.7Sodium stearoyl-2-lactylate 2.5 Calcium chloride 0.6 *Diacetyl tartaricesterified mono- and di-glyceridesMethod of Preparation of Gum Base

Polyvinyl acetate (10.65 g), Datem (4.14 g), acetylated mono-glycerides(2.76 g) and sodium stearoyl-2-lactylate (0.75 g) were heated to 110° C.with mixing. Acid casein (4.14 g), wheat gluten (3.6 g) and calciumchloride (0.18 g) were mixed into the first mixture until homogenous.Polyglycerol polyricinoleate (2.67 g) and lecithin (1.11 g) werecombined and added to the mixture (50° C.±10° C.). The mixture wascooled to 18° C.–20° C. and stored in an air tight container.

Chewing gum having the following formulation was prepared from the gumbase:

Ingredient % (weight/weight) Powdered sugar 44.0 Gum base 35.0 Glucosesyrup 20.0 Flavour 0.25Method of Preparation of Chewing Gum

Glucose syrup (84% solids) (5.0 g) was heated to 60° C. Gum base (8.8 g)was added and combined into the glucose syrup. Powdered sugar (11.0 g)was added slowly to the mixture and mixed until homogenous. Flavour(0.25 g) was mixed in gently. The gum was rolled into balls and storedin an air tight container.

Example 2

Ingredient % (weight/weight) Polyvinyl acetate (MW ~25,000) 35.5 Datem13.8 Acid casein 13.8 Filler (talc) 12.0 Polyglycerol polyricinoleate8.9 Acetylated monoglycerides 9.2 (Myvacet 7-07) Lecithin (Emulgum) 3.7Sodium stearoyl-2-lactylate 2.5 Calcium chloride 0.6

A gum base was prepared having the above formulation using the followingmethod: A Brabender Plasticorder (W 50 mixer, cam blades) was used, withan initial temperature of 100° C., and an initial speed of 60 RPM. Theacetylated monoglycerides, sodium stearoyl-2-lactylate and datem wereadded, followed immediately by the polyvinyl acetate. The temperaturewas then reset to 60° C. The casein and calcium chloride were added at 3minutes. The speed was decreased to 40 RPM just before adding thepolyglycerol polyricinoleate and lecithin at 8 minutes. The talc wasadded at 9 minutes and mixing stopped at 10 minutes.

Chewing gum having a similar formulation to that of Example 1 above wasprepared from the gum base using the following method:

A Brabender Plasticorder, fitted with a W 50 mixer (cam blades) andoperated at a temperature of 45° C. and a speed of 50 RPM was used asfollows:

-   1. The gum base and glucose syrup were mixed for 2 minutes;-   2. 33% of the powdered sucrose was added, and mixed for 2 minutes;-   3. 33% of the powdered sucrose was added with 50% of the flavours,    and mixed for 3 minutes;-   4. 33% of the powdered sucrose was added with 50% of the flavours,    and mixed for 2 minutes; and-   5. The gum mass was removed from the mixer and rolled to a thickness    of 2–3 mm.

Example 3

Ingredient % (weight/weight) Polyvinyl acetate (MW ~12,900) 15.0Polyvinyl acetate (MW ~14,000) 8.0 Polyvinyl acetate (MW ~25,000) 24.7Polyvinyl acetate (MW ~40,000) 5.3 Filler (talc) 8.5 Datem* 12.3 Acidcasein 6.1 Fine ground acid casein 6.2 Polyglycerol polyricinoleate 7.9Acetylated monoglycerides (Myvacet 7-07) 2.1 Lecithin (Emulgum) 2.2Calcium stearoyl-2-lactylate 1.2 Calcium chloride 0.5 *Diacetyl tartaricesterified mono- and di-glycerides

A gum base was prepared having the above formulation using a similarmethod to that of Example 2.

A chewing gum was then prepared having the formulation shown below,using the method described in Example 2, with the exception that theglycerol triacetate and stearic acid were also added in step 1.

Ingredient % (weight/weight) Gum base 24.60 Powdered sugar 49.92 Glucosesyrup 22.64 Glycerol triacetate 0.75 Stearic acid 1.00 Flavour 1.08

Examples 4–6

Gum bases having the following formulations were prepared, using thesame preparative method as that described above for Example 2, with theexceptions that, where antioxidant, paraffin and/or stearic acid wereincluded in the formulation, these were added together with the Datem,acetylated monoglycerides and calcium stearoyl-2-lactylate. Wherecarrageenan was present, this was added together with the casein and/orpolymerised casein (when present).

% (weight/weight) Example 4 Formula- Example 5 Example 6 Ingredientstion 1 Formulation 2 Formulation 3 PVAc (MW ~12,900) 15.0 15.14 8.15PVAc (MW ~14,000) 8.0 8.07 15.28 PVAc (MW ~25,000) 24.7 12.94 13.06 PVAc(MW ~40,000) 5.3 16.37 16.51 Filler (talc) 8.5 7.87 10.83 Datem(diacetyl tartaric 12.3 12.42 3.29 esterified mono- and di-glycerides)Acid casein 12.3 12.43 9.87 Polymerised casein 0 0 6.58 Polyglycerolpolyricinoleate 7.9 7.98 8.46 Acetylated monoglycerides 2.1 2.13 2.26(Myvacet 7.07) Lecithin (Emulpure N) 2.2 2.22 2.02 Calciumstearoyl-2-lactylate 1.2 1.21 1.28 Stearic acid 0.00 1.16 Calciumchloride 0.5 0.51 0.54 Paraffin 0.00 1.00 Carrageenan 0.72 0.76Antioxidant (Sustane 1F) 0.03

Chewing gums having the following formulations were prepared from theabove gum bases.

% (weight/weight) Example 4 Example 5 Example 6 Ingredients Formulation1 Formulation 2 Formulation 3 Gum base 24.60 24.98 24.97 Powdered sugar49.92 49.12 48.93 Glucose syrup 22.64 22.98 22.97 Glycerol triacetate0.75 1.00 1.20 Stearic acid 1.00 1.00 1.00 Flavour 1.08 0.93 0.93

The chewing gums were prepared using the same method as that describedabove in Examples 2 and 3.

Examples 7–12

Gum bases having the following formulations were prepared, using thesame preparative method as that described above for Examples 4–6. Wherepolymerised casein or hydrolysed polymerised casein was included, thiswas added together with the casein.

% (weight/weight) Ex. Ex. Ex. 7 Ex. 8 Ex. 9 10 11 Ex. 12 Ingredients F1F2 F3 F4 F5 F6 PVAc (MW ~12,900) 15.14 14.81 16.04 15.25 8.15 8.15 PVAc(MW ~14,000) 8.07 7.90 8.56 8.14 15.28 15.28 PVAc (MW ~25,000) 12.9412.65 13.71 13.04 13.06 13.06 PVAc (MW ~40,000) 16.37 16.01 17.34 16.4916.51 16.51 Filler (talc) 7.87 7.70 7.76 14.35 10.83 10.83 Datem* 12.4212.15 3.29 1.67 3.29 3.29 Acid casein 6.17 6.03 6.53 6.52 4.89 4.89 Fineground acid casein 6.26 6.12 6.63 6.63 4.98 4.98 Polyglycerolpolyricinoleate 7.98 7.81 10.58 9.88 8.46 8.46 Acetylated monoglycerides2.13 2.08 2.26 2.25 2.26 2.26 (Myvacet 7-07) Lecithin 2.22 2.17 2.352.02 2.02 2.02 Calcium stearoyl-2-lactylate 1.21 1.18 1.28 0.64 1.281.28 Stearic acid 0.00 1.08 1.17 1.16 1.16 1.16 Calcium chloride 0.510.50 0.54 0.54 0.54 0.54 Paraffin 0.00 1.08 1.17 1.00 1.00 1.00Carrageenan 0.72 0.70 0.76 0.76 0.76 0.76 Antioxidant (sustane 1F) 0.040.03 0.03 0.03 Polymerised casein 6.58 Hydrolysed 6.58 polymerisedcaseinMethod of Preparing Polymerised Casein

The “polymerised casein” referred to in Examples 4–12 is acid caseinwhich has been modified using the enzyme transglutaminase. This wasprepared using the following method:

A 0.1 M Tris-HCl buffer (pH 8.0) containing 5 mM CaCl₂, 10 mMdithiothreitol and 0.1% glycerol was prepared. Acid casein (7.5%weight/volume) and Guinea pig liver transglutaminase (0.015 units/mgcasein, Sigma) were added to the buffer. The solution was stirred andincubated at 37° C. until just prior to gelation. The reaction wasterminated in a microwave oven by heating the solution to 90° C.(Heating was preferable to inactivation using an EDTA solution since itwas thought some residual activity may persist during dialysis). Thesolution was dialysed in running water for 2 days followed by distilledwater for 1 day (with 3 changes of water) then freeze dried.

Method of Preparing Hydrolysed Casein

The “hydrolysed polymerised casein” referred to in Examples 7–12 is acidcasein which has been enzymatically hydrolysed and then repolymerisedusing the enzyme transglutaminase.

The method of preparation of the enzymatically hydrolysed andpolymerised casein was as follows: An enzymatically hydrolysed casein,which had been hydrolysed using porcine pancreatic trypsin, with adegree of hydrolysis of approximately 4% of the total number of thepeptide bonds, was selected as the starting material. A 0.1M Tris-HClbuffer (pH 8.0) containing 5 mM CaCl₂, 10 mM dithiothreitol and 0.1%glycerol was prepared. Hydrolysed casein (7.5% weight/volume) and Guineapig liver transglutaminase (0.015 units/mg casein, Sigma) were added tothe buffer. The solution was stirred and incubated at 37° C. for 5hours. The reaction was terminated in a microwave oven by heating thesolution to 90° C. The solution was dialysed in running water for 2 daysfollowed by distilled water for 1 day (with 3 changes of water) thenfreeze dried.

Chewing gums having the following formulations were prepared from thegum bases:

% (weight/weight) Ingredient A B Gum base 31.74 31.74 Powdered sorbitol41.39 41.39 Maltitol syrup 20.38 22.64 Mannitol 7.35 7.35 Glyceroltriacetate 2.00 2.00 Glycerol (96% solids) 2.26 Acesulfame K 0.75 0.75Flavour 1.40 1.40

The gum bases numbered F1, F2 and F3 above (Examples 7–9) were made intochewing gums having formulation A. The gum bases F2, F3, F4, F5 and F6(Examples 8–12) were made into chewing gums having formulation B. Thesechewing gums are all sugar-free.

Method of Preparation of Chewing Gum

The sugar-free chewing gum was produced from the gum base formulationsof Examples 7–12 using a Brabender Plasticorder fitted with a W50 mixer(cam blades). Temperature set at 45° C. and mixer speed at 50 RPM.

The chewing gum was produced in 3 steps:

-   1) Gum base, glyerol triacetate, maltitol syrup, mannitol and    glycerol (if included in formulation) were added to the mixer and    mixed for 3 minutes;-   2) The powdered sorbitol, acesulfame K and flavour were added, mixed    for 3 minutes;-   3) The gum mass was removed from the mixer and put through a set of    rollers so a product thickness of 3 mm were obtained.    Biodegradability/Disintegrability

The following test was carried out on two chewing gums according to thepresent invention.

Purpose:

Evaluate the biodegradability of two (2) dairy based samples withreplicates, exposed to Aerobic Diodegradation per ASTM D-5209 by contactwith activated sewage sludge innoculum. Compare the results to thebiodegradation rate of a positive control of cellulose.

Sample Identification: Source: A. (2 ea) Kiwitech Limited B. (2 ea) C.Cellulose Positive control (2 ea) AMC, Inc.

The formulations of the gum base compositions of samples A and B(examples of compositions of the present invention) are shown below:

A B PVAc (MW ~12,900) 20.0 21.9 PVAc (MW ~25,000) 33.0 36.1 Filler(talc) 6.5 1.5 Datem 12.3 12.3 Casein 6.1 6.1 Fine acid casein 6.2 6.2Polyglycerol polyricinoleate 7.9 7.9 Acetylated monoglycerides 4.1 4.1Lecithin 2.2 2.2 Calcium stearoyl-2-lactylate 1.2 1.2 Calcium chloride0.5 0.5Results:

The Aerobic Biodegradation per ASTM 5209 @ 20° C. testing of the twosamples showed the following in comparison to cellulose based on (%)carbon conversion efficiency:

Average Carbon Conversion (%) (Based on CO₂ Production) Sample A 28.86Sample B 31.14 Sample C Positive cellulose control 65.99

Cellulose had 100% weight loss indicating a successful test. Samples Aand B had over 90% weight loss. Some weight loss due to degradation butmost due to dissolving into solution. These results show that thechewing gums of the present invention disintegrated under the conditionsof the test.

Adhesion Characteristics of Chewing Gums of the Invention

Method:

The adhesiveness of a chewing gum of the present invention andconventional, commercially available chewing gums were analysed by thedegree of difficulty required removing the sample from a heated brick.For this test, 3–4 g of gum was chewed for 5 minutes, and then firmlypressed onto a brick preheated to 20° C., 30° C., 55° C. or 70° C. andthen held at that temperature for 48 hours at a relative humidity of50%.

After incubation the gums were removed from the bricks with a scraper,and the ease of removal was recorded. The experiment was repeated fourtimes.

Results:

Temp Residue Effort Stickiness ° C. A Conv A Conv A Conv 20 nonemoderate easy difficult very low high 30 none moderate easy difficultvery low high 55 none moderate easy difficult low high 70 low moderateeasy difficult low high Conv = Commercially available chewing gum A =chewing gum according to the present invention, having the sameformulation as that described in Example 3, with the exception thatglycerol triacetate was not included.

CONCLUSION

From this experiment, it can be seen that the two gums havesubstantially different adhesion properties. The gum of the inventionhas very low or no adhesion to a brick surface across a range oftemperatures. The conventional gum has a high adhesion to brick, whichmakes the gums difficult to remove across the temperature range sampled.

INDUSTRIAL APPLICATION

It is believed that chewing gums according to the present inventionprepared from a chewable gum base containing casein and/or modifiedcasein particles dispersed throughout a polyvinyl acetate matrix, willfind widespread acceptance with consumers.

Chewing gums according to the invention, at least in the preferredembodiments, have a combination of desirable properties. The gums whenfreshly chewed have been found to be sufficiently non-sticky that theycan easily be removed from most surfaces including carpet. If allowed todry on a surface the gum will easily flake off.

In addition, the chewing gums of the invention have been found to bedisintegrable and are made substantially of biodegradable components.

The gums of the present invention, at least in the preferredembodiments, exhibit good chewing properties, including good cohesionduring chewing and good “bubble blowing” properties. On chewing the gumshave been found to possess an excellent initial chew; the gum does notbreak into pieces on chewing but remains as one piece. The gums exhibitminimal change in firmness on chewing for 15 to 20 minutes with no toothtack or face tack.

In addition, at least in the preferred embodiments, the chewing gums ofthe present invention possess good flexibility and a desirableappearance.

It will be appreciated that the above description is provided by way ofexample only and numerous variations and modifications will be apparentto those persons skilled in the art without departing from the scope ofthe invention as defined in the following claims.

1. A chewable gum base composition comprising (a) a polyvinyl acetatematrix, wherein the polyvinyl acetate is in the form of a continuousphase, and (b) casein, a modified casein, or both casein and a modifiedcasein, wherein particles of casein and/or modified casein are dispersedthroughout the polyvinyl acetate matrix and wherein the polyvinylacetate comprises a blend of polyvinyl acetates having differingmolecular weights.
 2. A chewable gum base composition as claimed inclaim 1 which contains acid casein.
 3. A chewable gum base compositionas claimed in claim 1 which contains acid casein and fine ground acidcasein.
 4. A chewable gum base composition as claimed in claim 1 whichcontains acid casein and a modified casein, wherein the modified caseinis selected from casein polymerised using transglutaminase andhydrolysed casein polymerised using transglutaminase.
 5. A chewable gumbase composition as claimed in claim 1 wherein the casein, the modifiedcasein, or both, are present in a combined amount of about 5 to about30% by weight of the composition.
 6. The composition of claim 5, whereinthe casein, the modified casein, or both, are present in a combinedamount about 12 to about 16.5% by weight, of the composition.
 7. Achewable gum base composition as claimed in claim 1 wherein thepolyvinyl acetate comprises a blend of four polyvinyl acetates havingmolecular weights of approximately 12,900, 14,000, 25,000 and 40,000respectively.
 8. A chewable gum base composition as claimed in claim 1,wherein the polyvinyl acetate or a blend of polyvinyl acetates ispresent in the composition in an amount of from about 20% to about 65%by weight of the composition.
 9. The composition of claim 8, wherein thepolyvinyl acetate or blend of polyvinyl acetates is present in thecomposition in an amount of from about 35% to about 56% by weight of thecomposition.
 10. A chewable gum base composition as claimed in claim 1,which further includes a filler in an amount of up to about 25% byweight of the composition.
 11. A chewable gum base composition asclaimed in claim 1 which further includes talc as a filler, and ispresent in an amount of about 7% to about 13% by weight of thecomposition.
 12. A chewable gum base composition as claimed in claim 1which further includes one or more components selected from plasticizersand emulsifiers.
 13. A chewable gum base composition as claimed in claim1 which includes mono- and di-glycerides esterified with mono-acetyl anddi-acetyl tartaric acid, in an amount of about 1 to about 24% by weightof the composition.
 14. A chewable gum base composition as claimed inclaim 1 which includes acetylated mono- and/or di-glycerides, in anamount of up to about 24% by weight of the composition.
 15. A chewablegum base composition as claimed in claim 1 which includes polyglycerolpolyricinoleate, in an amount of about 4.4% to about 20% by weight ofthe composition.
 16. A chewable gum base composition as claimed in claim1 which includes lecithin, in an amount of up to about 6% by weight ofthe composition.
 17. A chewable gum base composition as claimed in claim1 which includes sodium stearoyl-2-lactylate or calciumstearoyl-2-lactylate, in an amount of up to about 5% by weight of thecomposition.
 18. A chewable gum composition as claimed in claim 1 whichincludes a calcium salt, in an amount of up to about 1.5% by weight ofthe composition.
 19. A chewable gum base composition as claimed in claim1 which further includes a protein-containing whey derivative.
 20. Aconfectionery product comprising a chewable gum base composition asclaimed in claim
 1. 21. A chewing gum comprising a chewable gum basecomposition as claimed in claim 1, and one or more components selectedfrom sweeteners and flavouring agents.
 22. A chewing gum as claimed inclaim 21, further including glycerol triacetate, in an amount of fromabout 0.5% to about 4% by weight of the chewing gum.
 23. A chewing gumas claimed in claim 21, further including stearic acid, in an amount offrom about 0.5% to about 1.5% by weight of the chewing gum.
 24. Achewing gum as claimed in claim 21, wherein the gum base composition ispresent in an amount of about 20% to 50% by weight of the chewing gum.